Sacajawea (Mizuo Peck), Atilla the Hun (Patrick Gallagher), Teddy Roosevelt (Robin Williams), Larry Daley (Ben Stiller) and Nick Daley (Skyler Gisondo) plot to save the magic that brought the museum characters to life in a scene from the motion picture "Night at the Museum: Secret of the Tomb." / Kerry Brown 20th Century Fox

by Bryan Alexander, USA TODAY

by Bryan Alexander, USA TODAY

Actress Marilu Henner recalls how elated she was to see her longtime friend Robin Williams looking so fit on the set of The Crazy Ones this spring.

"I could not believe how handsome and healthy he seemed," Henner says. "You can tell that about someone right away. He seemed to have this aura about him."

"But you don't really know what lies beneath," Henner says, choking up. "It makes me so sad that it came to this."

Williams was found dead in his Marin County, Calif., home Monday in an apparent suicide. Henner says the friend she started out in the business with in the late 1970s (Williams on the hit show Mork & Mindy, Henner on Taxi) seemed to be firing on all cylinders.

Williams had asked for her to appear on The Crazy Ones season finale as his ex-wife. He embraced Henner on the set when she arrived and then demanded to see pictures of her family on her smartphone.

"People would be surprised. He seems to 'on' all the time, but he was such a warm, cozy, friendly and loving person," Henner says. "And he was very interested. He wanted to see all of my pictures. He was one of those rare, real and interested people. It makes me cry just thinking about it."

Williams will be appearing in a bevy of upcoming films, including the recently wrapped Night at the Museum: Secret of the Tomb, where he has played Teddy Roosevelt in three chapters of the successful comedy franchise.

Museum co-star Dan Stevens told USA TODAY this month about the surreal-ness of shooting in the British Museum and having late-night conversations between takes with Williams near the famed Rosetta Stone.

Patrick Gallagher, who has portrayed Attila the Hun in all the series, says he recalls being jet-lagged and exhausted in between takes during the British Museum shoot. Williams approached him and started riffing about e-cigarettes in his comic-genius trademark style. The cast was soon in stitches.

Williams "just started this 10-minute riff of genius comedy, it was so fast. It was like he was trying to make me feel better and make me laugh," Gallagher says. "Everyone was sitting around laughing."

"It just shows he was just a very, very nice man," Gallagher adds. "It was just an honor to know him."

If there were further proof needed, Gallagher recalls having his 4-year-old niece declare she was hungry on the set of Museum when they were shooting in Vancouver.

"Robin Williams walked over to craft service and got her a muffin. And that sort of sums him up," Gallagher says. "He made everyone feel like an equal. He was a kind human being."

Williams had several other projects wrapped, including the voice part of Dennis the Dog in Absolutely Anything and the comedy Merry Friggin' Christmas (both films are seeking U.S. distribution). Williams was also in the early stages of a planned Mrs. Doubtfire sequel.

Henner would prefer to remember the fond memories on the Paramount lot when Mork & Mindy and Taxi were both filming.

"It was everyone, the Happy Days people, Laverne and Shirley. John Belushi was friends with Robin and would show up. We all had parties together," Henner says. "And the Taxi people had the best parties. Tom Hanks from Bosom Buddies was there. It was like we were all in high school together."

Four times a year, the weekly wrap party turned into a massive dance party with Williams grooving.